Methods and apparatus to use engine valves as both intake and exhaust valves

ABSTRACT

Methods and apparatus to selectively use engine valves as both intake and exhaust valves and to selectively operate the engine as a 2 cycle or as a 4 cycle engine. In a disclosed embodiment, the intake valves and the exhaust valves, are manifolded together through a small manifold, with the manifold being connectable to the intake manifold or the exhaust manifold through two-way valves. In preferably a camless engine, the engine valves may be controlled to operate the intake valves as intake valves only or to operate as both intake valves and exhaust valves, and to operate the exhaust valves as exhaust valves only or to operate the exhaust valves as both intake valves and exhaust valves. Exemplary embodiments are disclosed.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 60/775,387 filed Feb. 21, 2006.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of the operation and controlof engine valves in piston engines.

2. Prior Art

The present invention is based on the fact that at higher engine speedsand higher power outputs, engines have more difficulty breathing, thatis, their volumetric efficiency goes down. Typically modern engines mayinclude, by way of example, two intake valves and two exhaust valves percylinder to attempt to increase the volumetric efficiency. However,there is a limit as to how much this can achieve, as all four valvesmust generally fall within a circle of a diameter approximately equal tothe piston diameter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-section through an engine head illustratingone embodiment of the present invention.

FIG. 2 is an embodiment similar to that of FIG. 1, but using returnsprings for the air switch valves.

FIG. 3 is a top schematic view of the exemplary assembly of FIG. 1.

FIG. 4 is a cross section of an embodiment using poppet valves for theair switch valves, and corresponds to a cross section taken along lineA-A of FIG. 3.

FIG. 5 is another cross section of the embodiment of FIG. 4, thoughcorresponding to a cross section taken along line B-B of FIG. 3.

FIG. 6 is a schematic diagram for a V-6 engine incorporating the presentinvention.

FIG. 7 is a block diagram schematically illustrating the incorporationof the present invention in a multi-cylinder engine.

FIG. 8 is a block diagram of a multi-cylinder engine incorporating anembodiment of the present invention, together with a fuel injector percylinder, and a multi-cylinder engine controller.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention are intended to beused on diesel engines, though this is not a limitation of theinvention, as the invention is also applicable to gasoline engines, orengines intended to operate on other fuels. Also, while the presentinvention is preferably to be used on turbocharged engines, this too isnot a limitation of the invention, as the present invention is alsoapplicable to non-turbocharged engines. Further, the preferredembodiments are intended to be used on engines having multiple intakeand multiple exhaust valves, as is characteristic of most modernengines, though this too is a preference, not a limitation of theinvention.

The present invention is intended to increase the volumetric efficiencyof engines, in the exemplary embodiments disclosed herein, engineshaving two intake valves and two exhaust valves per cylinder, byselectively using all four valves, the two intake and the two exhaustvalves, as both the intake valves and as the exhaust valves for thatcylinder. For this purpose, much larger valves external to eachcombustion chamber are used to switch the coupling of the valves (intakeand exhaust) between an intake manifold and an exhaust manifold. Thusthe intake valves may be coupled as intake valves or exhaust valves,depending on whether it is an intake stroke or an exhaust stroke.Similarly, the exhaust valves may be coupled between the exhaustmanifold and the intake manifold, depending on whether they are thencurrently functioning as exhaust valves or intake valves. Because theseexternal valves can be large, they can be made to have low flowresistance, with the net result providing much better intake and exhaustbreathing for the engine.

The preferred embodiments of the invention are intended to be used inwhat are referred to as camless engines, wherein the timing andoperation of the engine valves may be electronically controlled (see forinstance, U.S. Pat. No. 6,739,293 entitled Hydraulic Valve ActuationSystems and Methods, the disclosure of which is hereby incorporatedherein by reference). While the preferred embodiments use electronicallycontrolled hydraulic valve actuation, other types of camless engineengine valve operation could equally as well be used. Because of thatdegree of control, an engine such as a diesel engine may be operated asa four cycle engine, or for higher power output, switched to two cycleoperation, as desired. Consequently, in a typical application of thepresent invention, a diesel engine may be operated as a conventionalfour stroke engine using two intake valves and two exhaust valves atidle and at low engine outputs, at higher engine speeds and outputs,perhaps operated with all valves functioning as both intake and exhaustvalves as described, and at still higher engine outputs operating as atwo stroke engine, again with all valves functioning as both intake andexhaust valves as described. This is merely one example of thecombinations of operating modes possible with the present invention.

FIG. 1 presents a schematic cross-section through an engine head showinga block 20, a piston 22 and two engine valves 24. These two enginevalves could be either two intake valves or two exhaust valves on therespective cylinder, with two such assemblies being used per cylinder inthis example. Two two-way air switch valves 26 and 28 are shown,operated by electronically controlled hydraulic actuators 30 and 32 atthe top of the Figure, with return pins 34 and 36 at the bottom beingalways subjected to hydraulic pressure for return of the air switchvalves to the upper position when the hydraulic actuators 30 and/or 32at the top of the air switch valves 26 and 28 are not pressurized. Atthe left side is the intake manifold INT and on the right side is theexhaust manifold EXH. These manifolds would be common to all cylindersof a multi-cylinder engine.

In FIG. 1, the right-hand air switch valve 28 is in its upper position,preventing flow from the engine valves 24, when open, to the exhaustmanifold EXH. At the same time, the air switch valve 26 at the left ofthe Figure is in its lower position, allowing flow past the enginevalves 24, when open, from the intake manifold INT to the cylinder. Thusthe two engine valves 24 shown, with the air switch valves 26 and 28 inthe position illustrated, function as intake valves. However, if the airswitch valves 26 and 28 are reversed in position, the two engine valves24 shown would function as exhaust valves.

The hydraulic control valves for the hydraulically controlled enginevalves and switch valves in this embodiment are shown schematically atthe top of FIG. 1. Hydraulic control valve HVA1 controls the two enginevalves 24 for the cylinder shown, with hydraulic control valve HVA2controlling the other two engine valves for that cylinder, not shown.Hydraulic control valves SW1 and SW2 control the switch valves 26 and 28for the two engine valves 24 for the cylinder shown, with hydrauliccontrol valves SW3 and SW4 controlling the other two switch valves forthe other two engine valves for that cylinder, not shown. Also in thisembodiment, an intensifier-type fuel injector may be used, such as onehaving direct needle control, and a selection of one, a second, or bothintensifier actuation piston areas to provide respective intensifiedfuel pressures for injection, as controlled by control valves INJ1, INJ2and INJ3. FIG. 2 is an embodiment similar to that of FIG. 1, but usingreturn springs 42 for the air switch valves 26 and 28.

A top schematic view of the exemplary assembly of FIG. 1 is illustratedin FIG. 3. Two engine valves 24 are operated in unison by a singleactuator 40 (FIGS. 1 and 2) controlled by control valve HVA1 as a resultof the BRIDGE shown in FIG. 1 and as illustrated in FIG. 3 as verticaldashed lines extending between two engine valves 24. The larger circlesare the associated air switch valves 26 and 28. While in FIG. 1 the airswitch valves 26 and 28 are shown as a form of spool/poppet valve, anytype of valve of adequate speed could be used. In that regard, note thatthese valves are not subjected to substantial pressure differentials,and accordingly, relatively simple valves of various configurationscould be used, including but not limited to rotary valves. Also, whiletwo, two way valves are shown, a three-way valve could be used ifdesired.

FIGS. 4 and 5 show schematic cross sections of an embodiment usingpoppet valves 26′ and 28′ for the air switch valves. These crosssections correspond to cross sections taken along lines A-A and B-B ofFIG. 3. This embodiment uses hydraulic return for both the engine valves24 and the air switch valves 26′ and 28′. Obviously however, the presentinvention is not limited to any form of engine valve return, or any formof air switch valves or operation thereof, provided they accommodate thedesired air flow area at least as large as the combined engine valvesthemselves, and more preferably at least twice or three times the airflow area of the combined engine valves. It is also not limited to anyform of engine valve actuation, provided the required control of enginevalve operation and timing are available.

FIG. 6 is a diagram illustrating an embodiment on a V-6 engine. In thisembodiment, a turbocharger Turbo having a TURBINE driven from eachexhaust manifold and driving an intake air COMPRESSOR is shown. Alsoshown is another Compressor driven by a hydraulic motor, augmented by ahydraulic accumulator. Obviously many variations of engine inlet airimplementations will be apparent to those skilled in the art.

Now referring to FIG. 7, a multi-cylinder engine is schematicallyillustrated. Each cylinder of the engine includes valves INV and EXVnormally functioning as intake and exhaust valves, respectively, bysetting the respective air switch valves to the appropriate position andleaving them there. However when desired, both intake valves INV andexhaust valves EXV for any, and usually all cylinders, can be used asboth intake valves and as exhaust valves whenever desired. The fuelinjectors normally used on such engines are not shown for clarity. Thereare of course small internal manifolds IM between the air switch valvesand the engine intake valves INV and the engine exhaust valves EXH,though preferably these manifold volumes are kept relatively small.

FIG. 8 is a block diagram of a multi-cylinder engine incorporating anembodiment of the present invention, together with a fuel injector percylinder, and a multi-cylinder engine controller. Normally thecontroller will respond to various inputs for control of engine valvetiming, the associated switch valves and injectors based on variousinputs, such as crankshaft angle and speed (measured or calculated fromthe changing crankshaft angle) and power setting, as well as otherparameters such as intake manifold pressure, air temperature, enginetemperature, etc. Note also, of course, the present invention may beused for engine compression braking, in the embodiment disclosed, usingall four engine valves per cylinder to vent each cylinder when thepiston is at or near top dead center. This venting may be to the exhaustmanifold, or to the intake manifold to recover some of the energy ofcompression when braking.

While in the preferred embodiments, when desired, all valves are usedfor both intake and exhaust, note that one could always use the intakevalves for intake and switch only the exhaust valves between functioningas exhaust and intake valves, or vice versa, thereby eliminating theneed for switching valves on the engine intake valves or the engineexhaust valves, respectively. The advantage, particularly with respectto increasing the volumetric efficiency on intake, is two-fold. First,less energy is lost by the pressure drop through the intake valves, andsecondly, more air is ingested, allowing injection of greater amounts offuel to obtain greater engine output. Thus both efficiency and maximumpower output are increased.

Thus the present invention has a number of aspects, which aspects may bepracticed alone or in various combinations or sub-combinations, asdesired. Also while certain preferred embodiments of the presentinvention have been disclosed and described herein for purposes ofexemplary illustration and not for purposes of limitation, it will beunderstood by those skilled in the art that various changes in form anddetail may be made therein without departing from the spirit and scopeof the invention.

1. A piston engine comprising: at least one intake valve and at leastone exhaust valve per piston engine cylinder; and, a flow control valvesystem for controllably coupling the at least one intake valve to anintake manifold or to an exhaust manifold, and for controllably couplingthe at least one exhaust valve to an exhaust manifold or to an intakemanifold; the at least one intake valve and at least one exhaust valveper piston engine cylinder being actuated by camless actuators.
 2. Thepiston engine of claim 1 wherein the flow control system comprises two,two-way valves per cylinder.
 3. The piston engine of claim 2 wherein foreach intake valve, a first two-way valve controllably couples the intakevalve to the intake manifold or blocks the coupling of the intake valveto the intake manifold, and for each exhaust valve, a second two-wayvalve controllably couples the exhaust valve to the exhaust manifold orblocks the coupling of the intake valve to the exhaust manifold, the atleast one intake valve and the at least one exhaust valve beingmanifolded together.
 4. The piston engine of claim 3 wherein a firsttwo-way valve controllably couples the at least one intake valve to theintake manifold or blocks the coupling of the at least one intake valveto the intake manifold, and a second two-way valve controllably couplesthe at least one exhaust valve to the exhaust manifold or blocks thecoupling of the at least one intake valve to the exhaust manifold, theat least one intake valve and the at least one exhaust valve beingmanifolded together.
 5. The piston engine of claim 1 further comprisinga control system for controlling the camless actuators and the flowcontrol valve system to operate the engine as a four cycle engine or asa two cycle engine.
 6. The piston engine of claim 1 further comprising acontrol system for controlling the camless actuators and the flowcontrol valve system to operate the engine using the intake valves forintake and the exhaust valves for exhaust, and to operate the engineusing the intake valves for both intake exhaust and the exhaust valvesfor both intake and exhaust.
 7. The piston engine of claim 1 wherein theflow control system couples the intake valves to the intake manifold orblocks the coupling of the intake valves to the intake manifold, andcouples the exhaust valves to the exhaust manifold or blocks thecoupling of the exhaust valves to the exhaust manifold, the at least oneintake valve and the at least one exhaust valve being manifoldedtogether.
 8. The piston engine of claim 1 wherein the piston engine is acamless engine further comprising: a control system for each cylinder tocontrol the intake and exhaust valves so that; at times, the pistonengine operates as a 4 cycle engine using the at least one intake valveas intake valves and the at least one exhaust valve as exhaust valves;and at other times, the piston engine operates as a 4 cycle engine usingall the intake and exhaust valves as intake valves and all intake andexhaust valves as exhaust valves.
 9. The piston engine of claim 8further comprising at still other times, the control system controls theintake and exhaust valves so that the piston engine operates as a 2cycle engine.
 10. The piston engine of claim 9 wherein the piston enginesometimes operates as a 2 cycle engine using all the intake and exhaustvalves as intake valves and all intake and exhaust valves as exhaustvalves.
 11. A method of operating a camless piston engine having atleast one intake valve and at least one exhaust valve per cylindercomprising: for each cylinder; at times, operating the piston engine asa 4 cycle engine using the at least one intake valve as intake valvesand the at least one exhaust valve as exhaust valves; and at othertimes, operating the piston engine as a 4 cycle engine using all theintake and exhaust valves as intake valves and all intake and exhaustvalves as exhaust valves.
 12. The method of claim 11 further comprisingat still other times, operating the piston engine as a 2 cycle engine.13. The method of claim 12 wherein the piston engine is sometimesoperated as a 2 cycle engine using all the intake and exhaust valves asintake valves and all intake and exhaust valves as exhaust valves. 14.In a piston engine, the improvement comprising: at least one intakevalve and at least one exhaust valve per piston engine cylinder; and, aflow control system for each cylinder for controllably coupling the atleast one intake valve to an intake manifold or to an exhaust manifold,and for controllably coupling the at least one exhaust valve to anexhaust manifold or to an intake manifold.
 15. The improvement of claim14 wherein the flow control system comprises one two-way valve perintake valve and one two-way valve per exhaust valve.
 16. Theimprovement of claim 15 wherein for each intake valve, a first two-wayvalve controllably couples the intake valve to the intake manifold orblocks the coupling of the intake valve to the intake manifold, and foreach exhaust valve, a second two-way valve controllably couples theexhaust valve to the exhaust manifold or blocks the coupling of theexhaust valve to the exhaust manifold, the at least one intake valve andthe at least one exhaust valve being manifolded together.
 17. Theimprovement of claim 15 wherein the piston engine includes multipleintake valves and multiple exhaust valves, the flow control systemhaving an air flow area at least as large as the combined intake andexhaust valve air flow area when coupling the intake and exhaust valvesto an intake manifold, and when coupling the intake and the exhaustvalves to an exhaust manifold.
 18. The improvement of claim 14 whereinthe flow control system couples the intake valves to the intake manifoldor blocks the coupling of the intake valves to the intake manifold, andcouples the exhaust valves to the exhaust manifold or blocks thecoupling of the exhaust valves to the exhaust manifold, the at least oneintake valve and the at least one exhaust valve being manifoldedtogether.